The potential pathophysiological role of platelet-activating factor in human diseases.

Platelet-activating factor (PAF) is a new phospholipid mediator released from various cell types and tissues by the catalytic action of phospolipase A2 and acetyl transferase upon immunological and non-immunological stimuli. It activates the cells by binding to specific binding sites. PAF exhibits a broad range of biological and pharmacological activities including platelet and neutrophil aggregation, eosinophil chemotaxis, bronchoconstriction, hypotension, and acute renal failure. In addition, PAF is involved in acute graft rejection, endotoxin shock, and gastrointestinal ulceration. Furthermore, it closely mimics the pathology of bronchial asthma and is cabable of producing most of the phenomena seen in inflammation. So far several PAF antagonists have been described and shown to afford protection. In future, pharmacological studies using such antagonists will help to elucidate the pathophysiological role of PAF in human diseases.